Finishing process incorporating improved catalyst systems to produce durable flameproofed cellulosic textile products with an excellent hand

ABSTRACT

IMPROVED CATALYST SYSTEMS HAVE BEEN FOUND THAT CAN BE USED IN PLACE OF THE CATALYST SYSTEMS PREVIOUSLY REQUIRED TO CURE FLAME-RETARDANT FINISHES FOR CELLULOSE TEXTILES. THESE IMPROVED CATALYST SYSTEMS CONSIST OF A MIXTURE OF ALUMINUM CHLORHYDROXIDE AND AN ACID SELECTED FROM THE GROUP PHOSPHORIC ACID, AXALIC ACID, LACTIC ACID OR A MIXTURE SELECTED FROM THE GOLLOWING: ZINC CHLORIDEGLYCOLIC ACID, MAGNESIUM CHLORIDE-CITRIC ACID, AND MAGNESIUM CHLORIDE-GLYCOLIC ACID. UNLIKE CELLULOSIC FABRICS TREATED WITH THE THP-AMIDE OR THPOH-AMIDE FINISHES WITH OR WITHOUT OTHER CATALYST SYSTEMS, FABRICS SIMILARLY PROCESSED WITH THE IMPROVED CATALYST SYSTEM, THAT IS, THE ONES CONTAINING ALUMINUM CHLORHYDROXIDE HAVE LOWER STIFFNESS VALUE AND A MUCH BETTER HAND.

United States Patent O 3,796,596 FINISHING PROCESS INCORPORATING nu- PROVED CATALYST SYSTEMS T PRODUCE DURABLE FLAMEPROOFED CELLULOSIC IEAIITILE PRODUCTS WITH AN EXCELLENT 5 ABSTRACT OF THE DISCLOSURE Improved catalyst systems have been found that can be used in place of the catalyst systems previously required to cure flame-retardant finishes for cellulose textiles. These improved catalyst systems consist of a mixture of aluminum chlorhydroxide and an acid selected from the group phosphoric acid, citric acid, oxalic acid, lactic acid or a mixture selected from the following: zinc chlorideglycolic acid, magnesium chloride-citric acid, and magnesium chloride-glycolic acid. Unlike cellulosic fabrics treated with the THP-amide or THPOH-amide finishes with or without other catalyst systems, fabrics similarly processed with the improved catalyst system, that is, the ones containing aluminum chlorhydroxide have lower stiffness value and a much better hand.

A non-exclusive, irrevocable, royalty-free license in the invention herein described throughout the World for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

FIELD TO WHICH INVENTION RELAT-ES This invention relates to the chemical finishing of cellulosic textiles. More particularly it relates to improved catalyst systems for use in the finishing process for producing durable flame-resistant cellulose-containing apparel and home furnishing textile items. Specifically it relates to catalyst systems that use aluminum chlorhydroxide in the treatment of cellulosic textile materials with the THP-amide and THPOI-I-amide finishes to produce durably flame-resistant products that have low stiffness values and excellent hand. THP or tris(hydroxymethyl)phosphine is a crystalline solid prepared by the 50 reaction of phosphine with three moles of formaldehyde in the presence of metal catalysts such as nickel chloride. THPOH or tetrakis(hydroxymethyl)phosphonium hydroxide is a solution prepared by neutralizingTI-IPC or tetrakis(hydroxymethyl)phosphonium chloride, with sodium hydroxide. The solution is considered to be a mix ture of products one of which is tris(hydroxymethyl) phosphine or TI-IP.

THE PRIOR ART Traditionally chemical finishing treatments to produce improved physical properties such as flame resistance in cellulosic fabrics have been carried out by pad-dry-cure procedures using a catalyst. That is, the solution of finishing agent and catalyst is applied to the fabric which is then padded by passing through squeeze rolls to adjust the pickup of treatment solution, dried to remove water or other solvent and then cure by heat treatment at relatively high temperatures (usually 150 C. or higher).

In recent years the THPOH-amide finish has been used 70 to produce durably flame-resistant fabrics. Although this finish does not usually utilize a catalyst, the efliciency of the process is good, but the fabrics are somewhat stiff and do not have an excellent hand. The finish and the process by which it is applied is taught in a publication by Beninate et al., An Economical Durable Flame-Retardant Finish for Cotton, Textile Research Journal 39, 368-374 (1969).

A similar finish, the TI-IP-amide finish, has been developed which normally uses a catalyst system. This catalst system usually is some type of Lewis acid or combination of Lewis acid and some organic acid such as magnesium chloride-citric acid. THP-amide treated fabrics are usually less stiff and have a better hand at comparable add-ons than those fabrics treated with the THPOH- amide finish. However, at add-on of 18-20% the stiffness values and hand approach those of the THPOH-amide finished fabrics.

THE PROBLEM Both the THPOH-amide and the THP-amide finishes, especially at high add-ons provide excellent flame resistance for cellulosic textiles. At high add-on this finish has two particularly bad disadvantages, high stifiness values and a harsh hand. This imposes a serious limitation on the attractiveness of both finishes as general commercial processes for flameproofing cellulosic textiles. Treated cellulosic fabrics which have been dried completely before testing need higher add-on than those not dried to pass the vertical flame test. Thus it becomes very important that a technique be available for adding high add-on of retardant without increasing stifiness. There has not been a catalyst system developed for the 'I'HP'OH-amide and THP-amide finishes to provide a finished fabric which has durable flame resistance, that is, pass the vertical flame test after complete drying and yet have low stiffness values and an excellent hand.

OBJECTS OF THE INVENTION It is the object of this invention to provide improved catalyst systems for the THPOH-amide and THP-amide processes which produce durable flame resistant cellulosic tfabricsr HOW THE OBJECTIVES ARE ACHIEVED We have found that a mitxure of aluminum chlorhydroxide, Al Cl(OH) and a Lewis acid such as lactic acid, is an excellent catalyst system for the application of the THPOH-amide and 'I'I-IP-amide finishes. The add-ons are high, that is, the efliciency of the process is very good and yet the stiffness values are lower than those shown by fabrics treated with these same finishes with the usual catalyst systems. The instant invention may thus be described as that in which the catalyst system is a mixture of aluminum. chlorhydroxide and a Lewis acid.

The textile material processed may be in the form of fibers, yarns, or fabric. The preferred form for treatment is fabric. The fabrics may be composed of cellulosic fibers,

, either natural, such as cotton, linen, ramie, and the like,

or regenerated fibers such as rayon, polynosic and the like. Furthermore the fabric may be cellulosic fibers, or woven from a blend of cellulosic fibers and synthetic fibers such as polyester, nylon, and the like.

The concentration of the THPOH-amide or THP- amide solutions may be varied in the range from about 5% to about 50%, based upon the total weight of the solution. The preferred range of concentration is from about 20 to 40%.

The Lewis acids, phosphoric acid, oxalic acid, tartaric acid, citric acid, trichloracetic acid', magnesium chloride, zinc chloride, lactic acid, glycolic acid and! mixtures of same are the agents of choice for use with aluminum chlorhydroxide in the process of this invention.

The catalyst mixture of aluminum chlorhydroxide and Lewis acid may be varied in composition from a ratio of 9 to 1 to 1 to 9. The concentration of the catalyst mixture may be varied from about .5% to 2% by weight based upon the total weight of the treatment solution. The preferred concentration is 1%. Neither of the components of the catalyst system if used alone, is suitable as catalyst in the treatment of the fabrics.

Impregnation of the fabric with the solution containing the finishing agent and catalyst system may be accomplished by any convenient means. conventionally this is done by immersing the fabric in the treatment solution, and passing through pad roll to adjust the pickup of solution and to give even penetration and distribution of the treatment solution throughout the textile material. The pickup of treatment solution in the wet, impregnated fabric can be adjusted within the range of from about 50% to about 120% based upon the dry weight of the untreated fabrics. The preferred wet pickup is from about 75% to about 100 based upon the dry weight of the untreated fabric.

SUMMARY OF THE INVENTION This invention may be described as an improved catalyst system for use in the finishing process for producing durable flame-resistant collulosic fabric. The finishing agents are the THPOH-amide and the Tl-IP-amide systems which are processed by a pad-dry cure procedure.

Example 1 A cotton flannel fabric (approximately g.) was padded twice with a solution containing 8.00 g. THP, 25.0 g. of 30% methylol urea solution (on the average each urea molecule contains 1.5 methylol groups), 2.5 g. trimethylolmelamine, .05 g. of a wetting agent, 1.0 g. of a softening agent, 13.33 g. water and 1.12 g. lactic acid (89% solution) to 80-90% wet pickup, then dried at 85 C. for 3 minutes and cured at 160 C. for 3 minutes. The fabric sample was then rinsed in hot tap water for minutes then dried. The fabric after equilibration had an add-on of 20.9% and a stiffness value of 28.5. The untreated control fabric had a stiffness value of 4.0.

Example 2 A cotton flannel fabric (approximately 10 g.) was treated with the ingredients and by the procedure of Example 1 except .05 g. aluminum chlorhydroxide and only 1.01 g. lactic acid (89% solution) was in the solution. The treated fabric had an add-on of 20.2% and a stiffness value of 7.0. The untreated control fabric had a stiffness value of 4.0.

Example 3 A cotton flannel fabric (approximately 12 g.) was treated by the procedure of Example 1 with a solution containing 18.75 g. of 40% aqueous THPOH, 5.25 g.

.urea, 4.75 g. trimethylolmelamine, .05 g. of a wetting agent, 1.0 g. of a softening agent, 2.5 g. ZnCl -glycolic acid solution in which each component had; equal molar amounts), and 17.70 g. water. The treated fabric after equilibration had an add-on of 20.27%, and a stiffness value of 26.0.

Example 4 A cotton flannel fabric (approximately 12 g.) was treated with the ingredients and by the procedure of Example 3 except 1.75 g. ZnCl -glycolic acid (20%) and 0.15 g. aluminum chlorhydroxide was used in place of the 2.5 g. znCl -glycolic acid. The fabrics after equilibration had an add-on of 20.1% and a stiffness value of 14.0.

Example 5 An x 80 cotton printcloth fabric sample was treated with the ingredients and by the procedure of Example 1. The fabric after equilibration had an add-on of 22.0% and a stiffness values of 7.5. The control fabric had a stiffness value of 3.5.

Example 6 A cotton sateen fabric (8 oz./yd. sample was treated with the ingredients and by the procedure of Example 1. The fabric after equilibration had an add-on of 16.4% and a stiffness value of 9.8. The control had a stiffness value of 19.5.

Example 7 A cotton flannel fabric (approximately 10 g.) was treated with a solution containing 7.11 g. tris(hydroxymethyl) phosphine 22.2 g. one and one-half methylolurea, 2.22 g. trimethylolmelamine, .05 g. of a wetting agent, 1.25 g. magnesium chloride-citric acid, (20%), .25 g. aluminum chlorhydroxide, and 16.92 g. water by the procedure of Example 1. The fabric after equilibration had an add-on of 16.4% and a stifiness value of 3.8. The control had a stiffness value of 4.0.

We claim:

1. A process for importing durable flame resistant properties to cellulosic textiles without imparting excessive stiffness, which process consists of:

(a) impregnating the cellulosic material with an aqueous solution comprising trimethylolmelamine, methylolurea, a methylol phosphorus compound selected from the group consisting of tris(hydroxymethyl)phosphine and tetrakis(hydroxymethyl) phosphonium hydroxide, and a catalyst system consisting of aluminum chlorhydroxide and a Lewis acid selected from the group consisting of phosphoric acid, lactic acid, zinc chloride-glycolic acid, and magnesium chloride-citric acid,

(b) drying the impregnated cellulosic material, and

(c) curing the dried cellulosic material.

References Cited UNITED STATES PATENTS 8/1963 Wagner et al. 117--137 1/1971 Moore 252-3 OTHER REFERENCES WILLIAM D. MARTIN, Primary Examiner H. J. GWINNELL, Assistant Examiner US. Cl. X.R. 

